Typical mountable wire shelving is comprised of two sets of a multitude of parallel wires, one set transverse, generally perpendicular, to and overlaying the other. The first set of wires is the structural or support wires which form the framework for the shelf, providing rigidity and torsional strength to the shelf. The second set of wires is the stringer wires which are transverse to and bonded/welded to the support wires, typically in a perpendicular orientation. The stringer wires form the upper surface of the shelves and serve as the support surface upon which items are placed in use. Typically, the support wires are of a greater diameter or width than the stringer wires, generally having a diameter or width of 150% to 400% or more of the diameter of the stringer wires.
Wire shelving is produced in continuous lengths of defined widths or depth of 12, 16, 18 and 20 inches. As a consumer product, wire shelving is typically sold as stock items of predefined lengths, e.g., 6 or 12 feet, which the installer then cuts to size. Wire shelving may be planar or have an “L” shaped cross-section along its width. Planar shelves have a linear cross-section and are characterized as having a plurality of support wires which run the length of the shelf, parallel to the mounting surface with a first support wire defining the front edge of the shelf, a second support wire defining the back edge of the shelf, and, optionally, though typically, one or more intermediate support wires there between. For example, a planar shelf having a 6 inch depth will typically comprise just the first and second support wires without an intermediate support wire whereas a planar shelf having a 12 inch depth or more will typically have one or more intermediate support wires which may be at or near the mid-point between the two edge support wires and/or aligned closer to the front edge support to provide additional torsional stability to the shelf under load. The stringer wires are likewise evenly spaced, perpendicular to the support wires and bonded or welded thereto, in either a loose mesh format, typically a 1 inch or so separation, or in a tight mesh format, typically a ½ inch or so spacing.
The more common wire shelving has an “L” shape cross-section where the back of the “L” corresponds to the shelf support surface whose length defines the depth of the shelf and whose construction mimics that of the planar shelf, as described above. The foot of the “L” corresponds to a front edge portion which is typically perpendicular to the shelf support surface and defined by the first or front edge support wire of the planar surface and another support wire parallel to and spaced from said first support wire, the spaced support wire. The front edge portion will typically have a height, i.e., the distance between the first support wire and the spaced support wire, of 3 inches or less, more commonly 2 inches or less. In some embodiments, the first and spaced support wires are connected by spaced rods or wires or equivalent elements which overlay the two or lie in the same plane as the two support wires. Alternatively, the stringer wires of the surface of the shelf are simply extended beyond and bent over the front support wire ending at the spaced support wire. The stringer wires of the “L” shaped shelves, like those of the planar shelf, are also of a loose or tight mesh construction. Finally, while the first, second and intermediate support wires of the planar support portion of the shelf may be in the same configuration as in the planar shelf itself, alternate configurations are also used depending upon the intended end-use of the shelving. Specifically, in addition to or in substitution for the support wires in the midpoint or mid-section of the planar shelf portion, one or more additional coplanar support wires are added parallel to and spaced from, but near, the front edge or second support wire. These wires add additional support and integrity to the shelf near the front edge of the shelf which is important for shelves with anticipated heavy loads, especially heavy loads towards the front of the shelf.
Owing to their simplicity and low cost, wire shelving has been a staple of consumers in installing shelving to pantries, closets, storage areas, etc. Along with the adoption of such shelving, a number of modifications and advances have been made for improved mounting and for allowing adjustments in the placement and size of the wire shelving. For example, Bertam (U.S. Pat. No. 4,624,376) discloses wire shelves wherein the vertical distance between shelves can be adjusted through the use of shelf supports secured to a wall or vertical mounting surface, which supports have a plurality of spaced slots for receiving tabs of a plurality of brackets which, in turn, support the shelf. Mastroclioasa (U.S. Pat. No. 4,669,692) employs support brackets that incorporate a slide element such that the shelf supported by the brackets may be extended and retracted to make items on the shelf more accessible.
While much of the art for adjustable shelves is directed to options for designing the shelf orientation and/or facilitating access to items on the shelf, several developers have addressed the need for adjusting shelf space. For example, Metcalf (U.S. Pat. No. 7,182,210) provides for adjustable shelving wherein the length of the shelf is extended through the use of retractable extension shelf units which pull out from the ends of the shelf. Lee (U.S. Pat. No. 46,446,658) increases the depth of the shelf through the combined use of slidable bracket supports and accordion-like hinged surface panels. Here, as one extends the shelf along the brackets, the accordion-like segments lie flat and provide additional shelf space. In reverse, as one retracts the shelf or pushes the shelf back along the slide, the accordion-like segments fold up. While effective, the shelving of Lee is complex and expensive with limited expansion capability.
Finally, Merl (U.S. Pat. No. 5,133,463) provides a two-piece shelf/bin assembly wherein the two pieces interconnect, with several connection points, to allow one to adjust the depth of the shelf/bin. Unfortunately, the design and construction as taught in Merl does not provide a planar shelf surface: thus, items placed on the shelf can tip over. Additionally, Merl requires that the shelf be emptied prior to making adjustments in the depth. Most critically, the number of possible configurations, hence depth adjustments, of the Merl shelf is limited by the number of intermediate support wires. If only one, then the shelf has just two configurations, that with and that without the extension. In this regard, Merl offers no or very limited versatility, especially if it is to be used with generally available wire shelving.
Thus, while improvements and advancements have been made towards making wire shelving more versatile to accommodate individual needs, especially in closet and pantry design, etc., there is still a need for more versatile and self-supporting shelf extensions for wire shelving.
Similarly, there is still a need for shelf depth extensions that provide and allow for a coplanar or substantially coplanar surface with the existing shelving.
There is a need for shelf depth extensions that can be adjusted to multiple depths: most especially where the adjustment can be made without the need to remove the contents from the shelf.
Furthermore, there is still a need for low-cost, simple shelving having adjustable depths: most preferably extension shelving of one piece and two-piece design which do not require tools for installation and which can be installed by individuals of even the most primitive of DIY skill sets.
Finally, there is a need for universal shelf extensions that are suitable for use with wire shelving of all or most all manufacturers and designs.